What YouTube asks for, and what this tool exports
YouTube's help page for custom thumbnails currently lists a resolution of 3840 × 2160 pixels, a 16:9 aspect ratio and a minimum width of 640 pixels, in JPG or PNG. The file limit depends on where you upload it: 2 MB from the mobile app and 50 MB on desktop (YouTube Help, checked 24 September 2026). Older guides, including earlier versions of this page, quote 1280×720 as YouTube's recommendation; the help page no longer says that.
This tool exports 1280 × 720. It is the same 16:9 shape, it is twice the minimum width, and at high JPEG quality it stays comfortably under the 2 MB mobile limit, so the same file uploads from a phone or a computer. If your source photo is genuinely 4K and you upload from a desktop, a larger thumbnail is allowed; most source photos are cropped too tightly for the extra pixels to carry real detail.
Start from the largest photo you have
Whatever size you export, a larger source photo helps the crop itself: it gives the focal-point crop more detail to work with before quality drops, which matters if you're cropping in tightly on a face or a product.
Why crop around a focal point instead of the centre
Very few source photos are already 16:9. A portrait selfie, a screenshot, a product photo shot in a different ratio — getting any of these to 1280x720 means cropping something, and a centred crop only works when the subject happens to already be in the middle. Dragging the focal point onto the face or object that has to read clearly builds the crop around that point instead, so a subject standing to one side of the original photo still ends up centred and legible in the thumbnail.
Design for small and covered
A thumbnail is judged at a fraction of its real size — often under 200 pixels wide in a mobile feed — and the bottom-right corner is covered by the video duration badge on most layouts. Two practical consequences follow from that:
- Keep the main subject — a face, the key object, any text you've added elsewhere — inside the central two-thirds of the frame, clear of the duration badge corner.
- Favour a small number of large, high-contrast elements over anything fine or detailed; detail that reads clearly at full size disappears at thumbnail scale.
This tool crops and resizes a photo to the right dimensions; it doesn't add text or graphic overlays. If your thumbnail needs a title treatment or arrows and circles, add those in an image editor after exporting the 1280x720 crop, so the photo underneath is already correctly framed.
File format and size
YouTube accepts JPG or PNG for custom thumbnails, up to 2 MB from the mobile app and 50 MB on desktop. This tool exports JPEG at high quality, which comes in well under the stricter mobile limit for a 1280x720 image while keeping the crop sharp — there's no need to compress it further afterwards. The current limits for other platforms are in our dated upload size limits table.
Everything runs in your browser using the canvas API. The photo is never uploaded to a server, there's no account or sign-up, and no file size limit beyond what your own device can handle.